Piping systems, such as those used to carry bulk materials, liquids, and the like, are often controlled using one or more multiple position valves which may be, for example, but are not limited to, butterfly and ball type valves, operated by a handle connected via a stem to the valve member. The valve members will typically have a closed position, a fully open position, and a range of partially open or intermediate positions between the closed and fully open positions, and the handle is typically rotated along an arcuate path about the stem body, to rotate the stem and the valve member within the valve body, to a selected position. The valve member must be securable in the closed position, and it is often desired to position and leave the valve member at the full or a partially open position to regulate flow through the piping system. To facilitate this, valves often include a notch plate mounted on the stem housing and including a row of notches defined by fingers positioned and configured to cooperatively receive a detent element such as a pin on the handle for holding it in the closed position, fully open position, and a selection of partially open positions. For piping systems used on trucks and trailers for carrying bulk particulate and powdered materials in at least the North America market, notch plates having either five or ten positions are the industry standards. The notch plates also typically include travel stops at the ends of the ranges of movement for preventing movement of the handle past the fully open and closed positions.
The known notch plates having a greater number of positions must have fingers that are relatively narrow. For strength, this necessitates that they be made from a relatively robust material such as steel. For aluminum valve stem housings, a separate steel notch plate is used, attached with fasteners, which increases cost and complexity.
In particular with regard to possible causes of damage to valve notch plates, during use, particulate and powdered materials can partially solidify and build up about the valve member within the valve body or housing, making movements to reposition or close the valve difficult. This can be the result of a variety of factors, including, but not limited to, inherent properties of the material, moisture, and/or temperature, e.g., freezing. The valves are often located beneath the bulk material containers of the truck or trailer, and thus are inconvenient to access, and truckers and other operators have been found to beat the handles with tools such as hammers and/or kick them, to free the valves. The detent element of the detent mechanism is often engaged with the notch plate of the valve as the handle is beaten, which can result in concentration of substantial forces against the notch plate, causing fingers to bend or break. This is a principal reason that notch plate fingers of weaker materials such as aluminum must be more robust and have fewer positions. A bent or broken finger, particularly for the closed position, can be a problem as it may prevent the valve from being securely held in that position.
Therefore, what is sought is a valve having a notch plate with enhanced strength, so as to be adapted to be cast in place on a valve housing or body of aluminum and other weaker and less durable materials, while provide more valve positions and greater adjustability.